The present invention generally relates to a water heater device and, more particularly, to a gas water heater and a method of operating the same.
Gas water heaters using natural gas such as LNG (liquefied natural gas), LPG (liquefied petroleum gas) or SG (synthetic gas) as fuel for heating water to a temperature level have been widely used. FIG. 1 is a schematic diagram of a conventional water heater 10. Referring to FIG. 1, the water heater 10 includes a combustion chamber 12, a pipe assembly 14 and a heat exchanger 15. High-temperature gas including carbon dioxide (CO2) and vapor are generated after the combustion. Cold water from an inlet (not numbered) of the pipe assembly 14 is heated when it passes through the heat exchanger 15. During the heating process, the heat exchanger 15 conducts a thermal exchange between the cold water and high-temperature gas. Consequently, hot water is supplied from an outlet (not numbered) of the pipe assembly 14. The conventional water heater 10 usually has a thermal efficiency ranging from 70% to 83%, which means that a considerable amount of heat energy generated during the heating process is dissipated, generally in the form of waste gas. The temperature of the waste gas is approximately 200° C. (degrees Celsius). Moreover, the vapor may condense into water drops that will yield condensed water. The condensed water may adversely affect the combustion, and may even erode the pipe assembly 14 and the heat exchanger 15.
It is desirable to have a gas water heater that is able to recycle waste gas so as to improve the thermal efficiency, and discharge condensed water, if any, in a more efficient manner.